Sail fabrics in present use are typically composed of woven fabrics, which are cut into panels of predetermined shape, and the panels are joined together along adjacent edges to make a sail. Laminated sail fabrics are also well known and include one or more films laminated to a woven or nonwoven substrate.
Materials used in sails are chosen on the basis of several properties such as flexibility, strength, stretch resistance, and resistance to tear. The resulting fabric should also have resistance to bias stretch, or stretch at an angle to the warp and fill directions of the fabric. Polyester yarns and films have gained wide acceptance as well as low stretch yarns of aromatic aramids and highly oriented polyethylene.
The use of films composed of liquid crystal polymers in sails is generally disclosed in U.S. Pat. No. 5,061,553, in which such films are used in combination with other films. Liquid crystal films are typically formed by an extrusion process and have a very high strength or stretch resistance in the axial or machine direction, i.e., the direction of extrusion. These films, however, are highly anisotropic and have poor strength and poor tear resistance in the cross machine direction.